(19)
(11) EP 0 023 491 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Mention of the grant of the patent:
28.03.1984 Bulletin 1984/13

(21) Application number: 80900048.2

(22) Date of filing: 13.11.1979
(51) International Patent Classification (IPC)3B01D 27/10, F16K 17/38
(86) International application number:
PCT/US7901/008
(87) International publication number:
WO 8001/465 (24.07.1980 Gazette 1980/17)

(54)

FILTER THERMAL BYPASS VALVE

THERMISCHES BYPASS-VENTIL FÜR FILTER

SOUPAPE BYPASS THERMIQUE DE FILTRE


(84) Designated Contracting States:
DE FR GB SE

(30) Priority: 22.01.1979 US 5626

(43) Date of publication of application:
11.02.1981 Bulletin 1981/06

(71) Applicant: INTERNATIONAL HARVESTER COMPANY
Chicago Illinois 60611 (US)

(72) Inventors:
  • RUBENSTEIN, Raymond D.
    La Grange Park, IL 60625 (US)
  • JANKE, Russell E.
    Naperville, IL (US)
  • RESCORLA, Charles L.
    Westmont, IL 60559 (US)

(74) Representative: Geldard, David Guthrie et al
Urquhart-Dykes & Lord Tower House Merrion Way
GB-Leeds LS2 8PB
GB-Leeds LS2 8PB (GB)


(56) References cited: : 
   
       
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] In fluid pressure systems, particularly hydraulic systems, it is important to prevent damage to the system components. Filtration of the fluid to remove contaminants therefrom before they reach the critical and expensive components, such as the pump and valves, is recognized as important and has long been accepted practice. However, should the filter element become clogged with contaminants, the pump could become starved for fluid, causing cavitation therein and permanent damage to the pump could result. Even if permanent damage to the pump is avoided in such a case, the flow of fluid from the pump into the hydraulic circuit may be insufficient for consistent and/or predictable operation of the equipment with which the hydraulic circuit is associated. In order to avoid pump damage and insure an adequate volume of fluid under pressure in cases where the filter element becomes clogged, it has been common practice to utilize the pressure differential created by such a clogged filter element to open a valve installed in a path parallel to the fluid filter in order for the fluid to bypass the filter element on its way to the pump. However, another cause of restricted flow through the filter is cold hydraulic fluid since cold oil has a high viscosity and cannot readily pass through the filter. In addition to the filter, the passages through which the fluid must pass also acts as a restriction to fluid flow. Hence, even if a bypass valve is used which is capable of opening in cold fluid conditions, for example as shown in US-A-2,729,339 the combined restriction of the passage and the filter, or filter bypass valve, can produce a total pressure drop greater than the pump can safely tolerate causing damage to the pump and/or producing inconsistent or erratic operation of the associated equipment.

    [0002] It is, therefore, an object of the present invention to provide a valve which will open in cold fluid conditions without creating a high pressure differential there-across, and which will automatically close when the temperature of the fluid reaches a predetermined value necessary for safe, consistent and predictable operation.

    [0003] According to the invention a thermal and pressure differential valve for a fluid filter comprises a valve housing adapted to engage one end of a cylindrical filter element, a valve seat surrounding an opening through the valve housing, a valve plate, a spring retainer, and a compression spring trapped between said spring retainer and said valve plate and urging said valve plate against said valve seat but permitting said valve plate to move away from said seat when a predetermined pressure differential exists across said valve plate characterised in that a mounting strap is affixed to said valve housing, a thermal actuator is affixed to said mounting strap, said actuator having a plunger movable towards said valve seat in response to increases in temperature, said spring retainer is slidably mounted in said mounting strap to be capable of movement towards and away from said valve seat, a rod member having an enlarged head portion is affixed to said spring retainer, said valve plate is slidably carried on said rod member between said head portion and said spring retainer, and a further compression spring is trapped between said valve housing and said spring retainer for forcing said spring retainer into contact with said plunger.

    [0004] The invention will become more readily apparent upon the perusal of the following description and the accompanying drawings, wherein the sole figure is a cross-section view illustrating a preferred embodiment of the invention in which a pair of valves are stacked to service two separate pumps.

    [0005] Referring now to the drawing, there is shown a portion of a housing 10 on a vehicle, such as farm tractor, having a cover plate 12 secured to the housing 10. A cap 14 is releasably secured, by means of bolts, not shown, for example, to the cover plate 12. The housing 10, the cover plate 12 and the cap 14 cooperate to form a sealed enclosure indicated at 15. A main suction pipe 16 leads from a reservoir and discharges into the enclosure 1 5. A first intake line 18 communicates with the enclosure 15 and leads to the inlet of a first pump, not shown. A second intake line 20, located in the enclosure opposite the intake line 18 communicates with the enclosure 15 also. The interior of the housing 10 is machined to permit the insertion, such as by press fit, of a position and seat member 22, which is designed to accommodate the larger opening end of a commercially available filter element 24. A first filter thermal bypass valve unit, indicated generally at 25, is fitted into the smaller opening in the other end 26 of the filter element 24. With the filter 24 and the unit 25 in such a position, it will be necessary for the oil to pass either through the filtering material in filter element 24 of through the by-pass valve 25 in order to get from the main suction line 16 to the inlet pipe 18.

    [0006] The interior of cap 14 is machined to form an annular seat 28, which is designed to accommodate the larger opening end of a commercially available filter element, which is designated by the numeral 30 but which is identical to the filter element 24. A second filter thermal bypass valve, indicated generally at 32, is fitted into the smaller opening end 34 of the filter element 30. The filter element 30 and valve unit 32 thus positioned, hydraulic fluid must flow either through the filtering material in filter element 30 or through the bypass valve 32 in order to get from the main suction line 16 to the pump inlet line 20.

    [0007] It will thus be seen that the filter element 24 and bypass valve 25 function exclusively with regard to the intake to the pump through intake line 18, while the filter element 30 and bypass valve 32 function exclusively with regard to the intake line 20 and its associated pump. Each of these assemblies are identical, the only difference being that they are reversed with respect to their orientation in the enclosure 15. It will be further appreciated that the filter element enclosure and both filters may readily be changed when they become dirty by simple removal of the cap 14. In order to make the assembly even more convenient, it is possible tqattach the element 25 and 32 together, in a manner to be described hereinafter, so that both bypass valve units 25 and 32 may be handled as a single unit. Since each of the bypass valve units are identical, the following detail description with regard to valve element 32 will be sufficient for a complete understanding of the valve unit 25.

    [0008] The valve unit 32 has a housing 40 including a flange 42 flaring outwardly from a tubular body portion 44. The tubular body portion 44 functions as a convenient guide to facilitate interengagement of the element 30 with the flange 42, the outer diameter of the portion 44 being substantially equal to the opening in the end 34 of the filter element 32. The housing 40 is also provided with a central opening 46 and an upraised seat 48. A spring 50 in a form of an elongate rectangular metal strip, is secured to the housing 40 by means of a rivet 52. The spring 50 serves to urge the unit 32 into tight engagement with the filter, and the filter into tight engagement with the seat 2.8 by being pressed into contact with the other unit 25. If the unit were used alone it would be necessary to provide a surface against which the spring 50 could be deflected in order to provide the proper spring load to assure good contact between the unit 32, the filter element 30 and the flange or seat 28 at the opposite end. The spring 50, being thin and bowed outwardly from the unit 32 also functions as a convenient handle for manipulation of the unit. The screen 54 is provided on the housing to remove the larger size contaminants from the fluid when flow is through the bypass valve opening 46. A mounting strap 56 is secured to the housing 40. A thermal actuator 58 including a plunger 60 is secured to the mounting strap 56, such as by trapping the thermal actuator 58 within a bore 62 provided in the mounting strap 56 between a flange 64 formed on the thermal element 58 and a snap ring 66 inserted in a groove formed in the thermal actuator on the side of the mounting strap 56 opposite the flange 64. The element 58 may be any type of device which can translate ambient temperature into a mechanical force, such as that marketed by Eaton Corporation, Controls Division, as a Dole (Trade Mark) power element, the specific one illustrated in the drawing being a Dole squeeze- push type power element F54-25.

    [0009] A spring retainer 68 is provided with outwardly extending tabs 70 which extend through slots 72 formed in the mounting strap 56. These tabs 70 serve to guide the spring retainer 68 in its reciprocating movement within the mounting strap 56. A rod member 74 is affixed to the center of the spring retainer 68 and is provided with an enlarged head 76 at its free end. A valve plate 78 is provided with a central bore 80 which permits relative movement along the axis of the rod member 74 between the valve plate 78 and the rod member 74. The valve plate is capable of engaging the raised seat 48 on the housing 40 to close off or seal the opening 46. An outer compression spring 82 is trapped between the spring retainer 68 and the housing 40. The function of the spring 82 is to ensure that the spring retainer remains in contact with the plunger 66 and also functions to ensure that the plunger 66 is returned when the thermal material within the actuator 58 contracts upon cooling. In returnning the thermal actuator 58 to its reset position when the system cools, the spring 82 also opens the bypass valve. An inner spring 84 is also trapped between the spring retainer 68 and the valve plate 78. This spring which is not as strong as the outer spring 82 functions to permit the valve plate 78 to open whenever a sufficient pressure drop occurs across the valve plate 78 as a result of the filter element 30 becoming clogged.

    [0010] The thermal actuator 58 contains a special material which expands greatly when heated, the expansion causing the plunger or piston 60 to extend from the actuator body forcing the spring retainer toward the seat 60 until the valve plate or disk 78 contacts the valve seat 48. By providing the bore 80 within the valve disk 78, the rod member 74 may move relative to the valve disk 78. This is important to prevent excessive loading on the thermal actuator since the thermal material continues to expand although perhaps at a slower rate, as the temperature continues to increase. Such continued temperature increase will cause the plunger to continue compressing the inner spring 84 as well as the outer spring 82 while the rod member 74 slides freely through the disk 78. Thus even though there is increased load on the thermal actuator, due to the further compression of both springs, there is some movement available and excessive loads on the thermal actuator are prevented. As the inner spring 84 compresses, the pressure drop across the filter required to open the valve disk 78 against the bias of the inner spring 84 increases and remains correct for the temperature at which the circuit is designed to operate. As the system cools off, the outer spring 82 forces the spring retainer against the plunger or piston 60 and resets the thermal actuator 58 by forcing the plunger 60 back into the thermal actuator body. As the spring retainer 68 moves toward the thermal actuator 58 the enlarged head 76 engages the valve disk 78 opening the bypass valve. When the hydraulic system is then subsequently started or operated in a cold condition the valve disk will already be displaced from the seat 48 permitting flow of the cold and viscous hydraulic fluid through the opening 46 without the necessity of any pressure differential being created in order to open the valve disk 78.


    Claims

    1. A thermal and pressure differential valve for a fluid filter comprising a valve housing (40) adapted to engage one end of a cylindrical filter element (30), a valve seat (48) surrounding an opening through the valve housing, a valve plate (78), a spring retainer (68), and a compression spring (84) trapped between said spring retainer and said valve plate and urging said valve plate against said valve seat but permitting said valve plate to move away from said seat when a predetermined pressure differential exists across said valve plate characterised in that a mounting strap (56) is affixed to said valve housing, a thermal actuator (58) is affixed to said mounting strap, said actuator having a plunger (60) movable towards said valve seat in response to increases in temperature, said spring retainer (68) is slidably mounted in said mounting strap to be capable of movement towards and away from said valve seat, a rod member (74) having an enlarged head portion (76) is affixed to said spring retainer, said valve plate (78) is slidably carried on said rod member between said head portion and said spring retainer, and a further compression spring (82) is trapped between said valve housing (40) and said spring retainer for forcing said spring retainer into contact with said plunger.
     
    2. A valve according to claim 1 characterised in that the valve includes spring means (50) for forcing said valve housing (40) into tight engagement with said filter element.
     
    3. A fluid supply unit comprising an inlet (16), a pair of outlets (18, 20) each leading to a separate pump, and a pair of thermal and pressure differential valves (25, 32) each as claimed in claim 1, each valve being operatively between the inlet and a respective one of the two outlets.
     
    4. A unit according to claim 3 characterised in that the two valves (25, 32) are inverted one with respect to the other and each includes a leaf spring (50) affixed to the valve housing (40) of the associated valve, the two leaf springs being secured together whereby the two valves may be handled as a unit.
     


    Revendications

    1. Soupape à commande thermique et à différentiel de pression pour un filtre de fluide, comportant une enveloppe de soupape (40) agencée pour coopérer avec l'une des extrémités d'un élément filtre cylindrique (30), un siège de soupape (48) entourant une ouverture pratiquée dans l'enveloppe de soupape, une plaque de soupape (78), un dispositif (68) de réception d'un ressort, et un ressort de compression (84) emprisonné entre ledit dispositif de réception d'un ressort et ladite plaque de soupape et solicitant ladite plaque de soupape contre ledit siége de soupape tout en permettant à ladite plaque de soupape de s'éloigner dudit siège de soupape quand un différentiel de pression prédéterminé existe de part et d'autre de la plaque de soupape, caractérisée en ce que: un bride de montage (56) est .fixée à ladite enveloppe de soupape, un dispositif thermique (58) de commande est fixé à ladite bride de montage, ledit dispositif de commande comportant un plongeur (60) qui peut se déplacer vers ledit siège de soupape en réponse à des augmentations de la température, ledit dispositif (68) de réception d'un ressort est monté coulissant dans ladite bride de montage pour être susceptible d'un mouvement de rapprochement et d'éloignement par rapport audit siège de soupape, un élément (74) en forme de tige, comportant une partie de tête élargie (76) est fixé audit dispositif de réception d'un ressort, ladite plaque de soupape (78) est portée de manière coulissante sur ledit élément en forme de tige entre ladite partie de tête et ledit dispositif de réception d'un ressort, et un autre ressort de compression (82) est emprisonné entre ladite enveloppe de soupape (40) et ledit dispositif de reception d'un ressort pour forcer ledit dispositif de réception d'un ressort à venir en contact avec ledit plongeur.
     
    2. Soupape selon la revendication 1, caractérisée en ce qu'elle comporte des moyens à ressort (50) pour forcer ladite enveloppe de soupape (40) à venir en contact étroit avec ledit élément filtre.
     
    3. Ensemble d'alimentation en liquide, comportant une entrée (16), deux sorties (18, 20) conduisant chacune à une pompe séparée, et deux soupapes à commande thermique et à différentiel de pression (25, 32), chacune selon la revendication 1, chaque soupape étant opéra- tivement disposée entre l'entrée et l'une, respective, des deux sorties.
     
    4. Ensemble selon la revendication 3, caractérisé en ce que les deux soupape (25, 32) sont en position inverse l'une par rapport à l'autre et comportent chacune un ressort à lame (50) fixé à l'enveloppe (40) de la soupape associée, les deux ressorts à lames étant assujettis l'un à l'autre, de manière que les deux soupapes puissent être manipulées comme un ensemble unique.
     


    Ansprüche

    1. Temperatur- und Differenzdruckventil für einen Flüssigkeitsfilter, mit einem Ventilgehäuse (40), das mit einem Ende eines zylindrischen Filterelementes (30) in Anlage bringbar ist, mit einem Ventilsitz (48), der eine Öffnung in dem Ventilgehäuse umgreift, mit einem Steuerkammerboden (78), mit einem Federhalter (68), und mit einer Druckfeder (84), die zwischen dem Federhalter und dem Steuerkammerboden eingespannt ist und den Steuerkammerboden gegen den Ventilsitz drückt, es jedoch dem Steuerkammerboden erlaubt, sich von dem Sitz wegzubewegen, wenn eine vorbestimmte Druckdifferenz über den Steuerkammerboden hinweg besteht, dadurch gekennzeichnet, daß ein Haltebügel (56) an dem Ventilgehäuse befestigt ist, daß ein temperaturabhängiges Verstellorgan (58) an dem Haltebügel befestigt ist, wobei das Verstellorgan einen Kolben (60) aufweist, der in Abhängigkeit von Temperaturanstiegen auf den Ventilsitz zubeweglich ist, daß die Haltefeder (68) gleitbeweglich in dem Haltebügel gelagert ist, um eine Bewegung auf den Ventilsitz zu und von ihm weg ausführen zu können, daß ein Stabteil (74) mit einem vergrößerten Kopfteil (76) an dem Federhalter befestigt ist, daß der Steuerkammerboden (78) gleitbeweglich zwischen dem Kopfteil und der Federhalter auf dem Stabteil geführt ist, und daß eine weitere Druckfeder (82) zwischen dem Ventilgehäuse (40) und dem Federhalter eingespannt ist, um den Federhalter in Kontakt mit dem Kolben zu belasten.
     
    2. Ventil nach Anspruch 1, dadurch gekennzeichnet, daß das Ventil eine Federeinrichtung (50) aufweist, um das Ventilgehäuse (40) in dichte Anlage mit dem Filterelement zu drücken.
     
    3. Flüssigkeitszuführeinheit mit einem Einlaß (16), einem Paar von Auslässen (18, 20), von denen jeder zu einer separaten Pumpe führt, und mit einem Paar von Temperatur- und Differenzdruckventilen (25, 32), jedesmal Anspruch 1, wobei jedes Ventil zwischen dem Einlaß und dem jeweils betreffenden der beiden Ausläße in Arbeitslage angeordnet ist.
     
    4. Einheit nach Anspruch 3, dadurch gekennzeichnet, daß die beiden Ventile (25, 32) bezüglich zueinander umgedreht angeordnet sind und je eine Blattfeder (50) aufweisen, welche an dem Ventilgehäuse (40) des zugehörigen Ventils befestigt ist, wobei die beiden Blattfedern aneinander befestigt sind, wodurch die beiden Ventile als Einheit handhabbar sind.
     




    Drawing